1. Agthe., C: Über die physiologische Herkunft des Pflanzennektars. Ber. Schweiz. bot. Ges. 61., 240–273 (1951).
2. — Andel., O. M. van.: Determinations of the osmotic value of exudation sap by means of the thermo-electric method of Baldes. and Johnson.. Proc. Kon. Ned. Akad. Wetensch., Ser. C 55., 40–48 (1952).
3. — Arber., A.: Studies in flower structure. II. On the vascular supply to the nectary in Ranunculus.. Ann. of Bot. 50., 305–319 (1936).
4. — Arisz., W. H.: Permeability in plants. Acta physiol. et pharmacol. néerl. 3., 575–599 (1954).
5. Behrens., W. J.: Die Nektarien der Blüthen. Anatomisch-physiologische Untersuchungen. Flora (Jena) 62., 2–11, 17–27, 49–54, 81–90, 113–123, 145–153, 233–240, 241–247, 305–314 369–375, 433–448, 449–457 (1879).